Wednesday, June 24, 2009

US Patent 7550747 - Nanotip electron beam maskless lithography

Since electron beam lithography usually uses only a single electron source it is usually considered too slow to be used in the semiconductor processing necessary for mass production. However, the inclusion of massively parallel arrays of electron sources can increase throughput. This patent teaches using a high density of carbon nanotube electron emitters as both a lithography tool and an alignment sensor. Claim 1 reads:

an array of lithographic nanotips capable of electron emission formed substantially normal to the first side of the substrate;

a target to be lithographically patterned by the array of lithographic nanotips; and

an array of sensing nanotips formed substantially normal to the first side of the substrate and provided on at least two sides of the lithographic nanotips so as to provide an alignment reference for the lithographic nanotips,

wherein the array of lithographic nanotips is formed in a pattern corresponding to a desired lithographic pattern on the target to be processed and wherein the apparatus is constructed to allow at least a portion of the first side of the substrate to contact the target during lithography.